Sudoku Primer 322 - Quadruplets: Useful, But Hard to Find

[@francespotter7697]

Gotta love that DRE technique. I never think to look for it. Useful as always, thankyou Harold 🙂

[@wordoku]

Very welcome. Practice those DCEs and DREs and you'll find them easier!

[@adleyg5986]

I got stuck pretty quick but was eventually able to open it up after spotting the 39, 47 and 15 twins in row 3. And then finding the 14 twins in box 1. Always a Good Friday when I can solve Harold’s puzzle. Thx Harold.

[@wordoku]

You're welcome! And nice work solving it.

[@CyeMourii]

Thank you for the enjoyable solve

[@wordoku]

Very welcome! Thanks for the comment.

[@vijayaragavand9474]

Nice puzzle n quite interesting . Absolutely enjoyable.

[@wordoku]

Glad you enjoyed it!

[@georgegamentzy1816]

This one had started out scary, then everything fell into place. Good brain exercise!

[@wordoku]

I agree!

[@georgesthibaudeau1533]

Brilliant. I never found the box1 quads. I came very close working from the 28 twins plus 157 triplets in col 5 but twice I made some error at a point I cannot remember although I had the correct solution for col 5. Damn me !

[@wordoku]

This was a tricky puzzle. Good work anyway!

[@grahamfisher307]

OK, I see the quadruple from the video now, and I can see why I bypassed it. I saw the 3 & 9 pair in C1 & 3 of R3, R1C3 had to be 5 the R3C2 had to be 7, leaving the 1 & 4 pair in C1.

[@wordoku]

I found later that you can find the 14 pair (without finding the quadruplets) in box 1 by knowing that 9 is constrained to row 3 in box 1. Good show.

[@AnonimityAssured]

I'd normally get down to this with fervour, but I'm all sudoku'd out for the day. It took me 127 levels to reach Rank 1 in the latest online tournament, called Halloween. (Oh, how I miss that beautiful apostrophe in 'Hallowe'en'!) It's only the first day of the tournament, and I'm all but burnt out. Already, by now, my rank will have dropped considerably, but just for a moment, I was up there. No record times as yet, but a fair average speed, and always without notation. Well, I couldn't resist the lure for long. With my batteries partially recharged, I braved the grid once more (96 = row 9 column ): 96, 38, 56, 32, 36, 72, 89, 13, 26, 27, 11, 21, 83, 24, 75, 46, 45, 35, 29, 39, 14, 64, 66, 65, 55, 86, 63, 58, 59, 78, 84, 74, 86, 81, 33, 31, 79, 97, 18, 77, 19, 17, 99, 71, 52, 42, 57, 47, 54, 44, 53, 51, 93, 91, 92. No explanation of individual steps. I saw quite a few pairs and a triplet, but no quads, as far as I remember.

[@wordoku]

Good luck in the tournament!

[@AnonimityAssured]

@@wordoku Thanks a lot, Harold. At the halfway stage, 180 grids, I got back up to Rank 65. I'd fallen to Rank 250-ish overnight. I'm not really concerned about the result, though. For me, it's simply a chance, and a motive, to get some serious practice. 180 grids in two days is a real workout. My Sudoku production line is on hold just at the moment, but I have a few good ones in the warehouse.

[@wordoku]

@@AnonimityAssured That's a lot of grids!

[@AnonimityAssured]

@@wordoku It is, but most of them are easy, and can be done in well under two minutes.

[@surendralov4164]

Hard puzzle.

[@wordoku]

Yes

[@grahamfisher307]

I removed the comment after spotting a ghastly error, started again and got the solution fairly easily, since the crucial move applied still. I didn't spot a quadruple, strangely enough, so my perspective (as is the case sometimes) must have been different. I solved using pairs, the initial one being the 4 & 7 in C3. The next one was key, when in conjunction with one end of 4 & 7 pair, I was able to confine the number 3 and 9 in two cells of block 1, that block essentially unlocking the whole thing. That pair placed firstly a 5, then 7 (resolving 4 & 7 pair in C3) and giving a 1 & 4 pair. I did use a UR in block 9 to disambiguate things there.

[@wordoku]

You saw it differently than I did.

[@grahamfisher307]

@@wordoku Yes, as often the case. I suppose my approach is simply one of 'what can I see?' rather looking for a particular situation.